Hi Guys. Ive been away for a while, but the progress on the boat is going nicely.
She is now under roof. Its nice to be able to work when its raining and leave the tools out at night. I'm thru with the sand blasting. The hull has three coats of Amercoat 240 inside and out and the exterrior faired. Finish coats will be applied later. It looks good even if I do say so myself. I have fabricated the wheel house windows and the forward hatch. I'll have to wait for warmer weather to glass the deck. I have located a local supplier for the polyIso spray foam. The lumber is at 10% moisture content for the inside work.

+1. Use 407 for general fairing and 410 for final fairing/pinhole filling only. I can't imagine fairing in 404. Must have been work. Another thing to keep in mind is that 407 is made for fairing and is a little more flexible, which helps it maintain it's bond. You want the fairing to flex at the same rate as the substrate, ideally.

Thanks for the input. Hope I didnt screw it up. I didnt have to do much build up. Mostly I skimmed the surface to get rid of the "old steel" texture and to dress up a few crappy looking welds.

It'll probably work out fine. Another point is that 407 and especially 410 give you a lot more fairing compound per volume of epoxy, ie a quart of resin thickened with 404 actually gives you less than a quart of filler, but a quart of resin mixed with 407 gives back a good 1 1/2 qt. of filler, 410 2 qt. or more. This makes a huge difference in economy.

Time for another update. Inside the hull, below the waterline, got sandblasted and painted with the same stuff I painted the outside with. (Americoat 240) . Blasting inside the hull makes one hell of a mess - I dont reccomend it. It took all day to clean up and pressure wash the entire inside of the boat to get the grit out. I had to cut a few lubber holes (is that the right word) so all the water drained to the bilge. It looks so nice I dont want to cover it up.
I think if the paint will protect the out side from salt water, it sould work on a little condensation.

I got 2 sample cans of expanding polyiso foam today. Its marketed as a closed cell fire retartant foam. I'll play with it for a few days before I decide if I'm going buy the 2-600 board feet cannisters I'll need to do the boat.
I think most folks use polyurathane foam. Has anyone used expanding polyiso inside the hull on a steel boat down to the water line? How did you like it?

I plan to apply this stuff to some scrap steel and test the "fire retardant" aspect. Should be fun

The fire test went well. I'll post the video later. I put a layer of expanding polyiso on a 3/16 plate, let it cure for 10 minutes then cut the plate in half with an acetylene torch. The flames went out in less than 15 seconds.

I did the same with polyurathane foam, styrofoam and the "great stuff" from lowes - they all burned until the foam was gone.